1. Field of the Invention
The present invention is an improvement to nut harvesters generally of the type of harvester taught in our earlier U.S. Pat. No. 5,001,893 issued Mar. 26, 1991. The improvement taught in the present disclosure involves the use of multiple debris discharge openings in a single fan housing of the air moving system used to remove debris from the nuts as they are picked up from the ground.
2. Description of the Prior Art
Modern nut harvesters or nut pick-up machines which lift nuts (agricultural items) from the ground in an orchard of trees for deposit into a container such as a trailer or large box, typically use suction fans and ducting to draw air through open conveyor chains on which the nuts are deposited immediately after being lifted from the ground. The air drawn through the open conveyor chain lifts dirt, leaves, small stick and like debris into the ducting system, and thus separates the unwanted debris from the nuts. The debris is carried through the ducting to the suction fan and fan housing wherein the air and debris is moved from the suction side of the system to the pressure or exhaust side of the system to be ejected through a single exhaust duct of the fan housing out onto the ground.
Normally, for reasons pertaining to cost of manufacture, number of parts to be serviced, power consumption (fuel), and simplicity of operation and control, most modern nut pick-up machines utilizes only a single and relatively large debris removal fan contained in a fan housing having a single intake (suction) duct and a single exhaust duct on the fan housing on the harvester. Some nut harvesters of the past have used multiple debris suction fans and multiple fan housings, an arrangement which has significant drawbacks compared to the use of a single fan typical of more modern pick-up machines. Additionally, most all nut harvesters eject the debris to one side of the harvester, with this being to aim the debris away from the front of the harvester where the driver or towing tractor is positioned, and away from the nuts which have already been cleaned and deposited in a storage container positioned at the rear of the harvester.
The use of a single exhaust duct or outlet from the fan housing on such harvesters has been found to have a number of problems which the present invention solves.
One of the significant problems associated with the use of a single exhaust duct on a debris removing fan is a high amount of wear on the fan and fan housing. This wear is the result of some of the debris entering the fan housing a substantial distance from the exhaust outlet, and therefore the debris remains within the housing an extended period of time while it travels the extended distance toward the exhaust outlet. The debris, being highly abrasive, wears the expensive housing and fan, and the longer period of time the debris remains in the housing, and the longer the distance the debris must travel within the housing to the exhaust duct, the greater amount of wear the debris applies to the fan and fan housing. It would be desirable to have the fan and fan housing last as long as is possible since the servicing or replacing of these components costs time and money, and therefore adds to the overall cost of harvesting.
Another of the significant problems associated with the use of a single exhaust duct on a debris removing fan housing is the tendency for the debris, particularly wet debris, to cause clogs or clogging, usually in the bottom of the housing. Such clogging can greatly reduce the ability of the incoming debris to be ejected from the housing, and once a clog begins, it oftentimes becomes rapidly worse, leading to the harvester needing to be stopped and the fan housing opened and cleaned out. This cleaning of the fan housing costs time, and therefore is undesirable. Additionally, the clogging, depending on the severity thereof, may go unnoticed by the operator for a period of time. The clogging can lead to higher back-pressure and reduced air movement (suction) through the conveyor chain on which the nuts are carried, and this can lead to an excessive and undesirable amount of debris remaining in the nuts when they are deposited into a storage container. The problem with clogging is in part related to the time and distance the debris remains and travels within the fan housing, as the debris, particularly when wet, can be heavy and sticky, and can lose some of its velocity prior to being ejected out the exhaust duct. It is always desirable to have as much of the debris removed from the nuts as is possible prior to the nuts being deposited into the storage container, and to this end, the suction applied to the chain on which the nuts are conveyed is normally initially set at a maximum strength, being just slightly less than what would draw the nuts themselves into the debris removal fan. Only a small amount of build-up or clogging in the fan housing will lead to increased back-pressure and thus reduced suction applied over the conveyor chain, and thus a greater amount of debris left in the nuts when they are deposited in the storage container. Nuts are normally purchased by weight and quality, and cleanliness is a quality aspect, and an excessive amount of debris remaining in the nuts will lead to the purchaser paying significantly less per weight unit. Therefore, it can be appreciated that constant and predictable air drawing through the conveyor chain and nuts thereon is highly desirable for proper cleaning.
Another of the problems associated with the use of a single exhaust duct on a debris removing fan is the excessive back-pressure which is normally overcome by use of a substantially large fan. The inability of a debris removal fan to rapidly exhaust air effects its ability to create suction on the open conveyor chain which can lead to an excessive amount of debris remaining in the nuts. The ability of a debris removal fan to exhaust air is effected by a number of factors such as size of exhaust outlet relative to fan and intake duct size, R.P.M. of the fan, and whether any clogs or clogging has accumulated in the fan housing or exhaust duct. Generally, the larger the fan, the higher the cost of manufacture thereof, and the greater amount of power (fuel) needed to operate the fan, and so it would be desireable to use a smaller fan to achieve the same results as a larger fan when possible.
Another of the problems associated with the use of a single exhaust duct on a debris removing fan, and one which is receiving increasing attention, includes an excessive amount of dust which may be created by high volumes of rapidly moving exhaust air throwing dust and debris into the air or striking the ground and creating dust clouds. The amount of dust is of course dependent upon whether the ground is dry or moist. Harvesting during dry weather is normally preferred, although the rains sometimes come early, requiring wet nuts to be picked up. When harvesting in dry weather, high volumes of dust, or dust clouds serve no useful purpose, and it is becoming increasingly clear that orchard dust can pose health problems for humans as well as for the orchard trees. Such clouds of dust can blow a significant distance, and can invade nearby homes and can be taken into the lungs. Many believe such dust is harmful. Additionally, blowing dust can carry disease from tree to tree, or from orchard to orchard.
Therefore, there is a need for further improvement in nut pick-up machines, and particularly in the portion which utilizes air movement for removing the debris.